Approach to Harmonics

[RossH]

Through serendipitous circumstance, I ended up talking to Ken Fischer for a few hours the other day. Great guy! Ken is a special and uncommon man. Very kind. His approach is so different than what I see in the typical amp builder today.

If I was going to summarize my feelings of what Ken would say about amp building it would be this: "EVERYTHING matters...listen, learn, experiment (REPEAT). It's taking the whole organic approach to your art.

I didn't want to ask him the same old "what value is this...or that" question. And I didn't want to waste his time since he isn't feeling all that great and was working on Mark Knopfler's and Richie Sambora's 'Ken-tuned' Komet at the moment.

So I asked: "What approach do you take to amp building that makes them so harmonically rich?"

And my short-form, paraphrased, interpretive response from him:

"Instability. Think of airplanes. An F-16 is basically unstable but can turn around instantly and rocket all over the place. A 747 is stable and takes 2 miles to turn around. I build rock lead amps. They aren't for everyone because they don't hide your playing and they are very responsive in their particular application. If you don't have good control over your guitar you may not like them that much. Anyway...what I do is build them with a simplicity that ends up inherently unstable at the outset. Then I use various techniques to bring them to the edge of stability. Right there on the edge. I don't use caps across the plates and all the band-ade devices if at all possible because those take away your harmonics along the way. When I first power up an Express, they howl and scream until I tweak things. Without the "fixes" and "band-ades" they have the most harmonic range to them. I try to fix them without losing that harmonic range. This is where everything matters. No two Expresses are exactly the same amp. I have a rating scale from 1 to 10. If an Express doesn't at least reach a easy 7, I would remove it from the cabinet, torch it and start over. These amps are meant to be played. I want people to USE them...not collect them. They are meant to be on records, in clubs, and at jams."

I told him that when I looked at some of the derived Express schematics it looks similar to a ...and he said they aren't modeled after ANYTHING. If they resemble a Bassman, or what have you, it is purely coincidental. If you look closely (where EVERYTHING matters) they are completely different amplifiers.

Anyway, I just wanted to share, with the Trainwreck group, this bit of our conversation.

Ross

[Omar]

Wow Ross. That's an awesome post. How did you happen to speak to him? Can you give us an update on Ken's health? Is he getting better or worse?

The stability thing is definately the key. I had to use of band aides (grid stoppers, cap across the plates of the phase inverter, shielded cable) to control my Twreck clone. It was so unstable when I first fired it up.

Omar

[Fred]

Hi Omar, Ross is about to help us at Ultlimate Guitar Gear to write some more stuff that Ken wants to share with our readers.
Kens health is not that good at the moment

We will let you all know when we have some more material published on our website.

br / Fred

[Omar]

Fred - Thanks for the update. Please give Ken our best. I was wondering why there hadn't been any updates from Ken UGG but I guess we know why.

Let us know when you post an update on UGG.

Omar

[RossH]

Omar,

Ken said (as Fred did) that he is not feeling very well. He also said that he is very busy and has a LOT of requests to do things. He said that the work he does perform suits him today because people let him do it "on his own time".

I will say that he seem to be in good spirits.

Ross

P.S. He did say another thing. He felt that women and children could generally hear better than men so he had them do tonal assessments often...if nothing else for comparative purposes.

[LeftyStrat]

"Then I use various techniques to bring them to the edge of stability."

He didn't by chance mention any of these techniques? I've read speculation that he may have played around with the layout (ampage threads on parasitic oscillations and such). If he's not using any bandaid techniques, the only other thing I can think of is component substitutions, which I guess may explain the various different schematics.

Thanks for this, it confirms some of my own suspicions with regard to instability, not only in lead/high gain amps, but even in cleaner amps. I guess being on the edge means the amp will be more reponsive to playing, barely stable and every note pushing it into some chaotic realm.

[RossH]

He didn't by chance mention any of these techniques? I've read speculation that he may have played around with the layout (ampage threads on parasitic oscillations and such). If he's not using any bandaid techniques, the only other thing I can think of is component substitutions, which I guess may explain the various different schematics.

This is where I ended up concluding that "everything matters". He confirmed this. He talked about layout/lead dress, component quality, component substitution, wire type/makeup, wire covering, soldering techniques, solder makeup, directional (or polar) component ideas, tubes, tube bases, transformers inside and out, and in general he approached a layer of subtlety that I am not use to hearing about in relation to tube amps. He said he still has everything to make an Express except the PS caps. He didn't specify the "if this...then that" approach. Maybe he will enter that zone when he resumes writing.

You could almost say that he views things in relation to the frequency/harmonic response or impact to the signal at the level of the grain structure of the wire and other components. I know that sounds intense...but this is what I am left with. He gave a lot of views on a lot of things. Heck, he even mentioned studying the frequency/harmonic impact of the various color dyes used in teflon wire coatings. All of a sudden, things are sounding kind of hi-fi, eh?

Ross

[ODwan]

Yeah, those hi-fi mojo dudes...
But I experienced it myself once:
I built a Plexi clone which was oscillating at about half the turn of the volume knob no matter what I did about it! One day I wanted to add another bandaid and accidently cut the wire to the 2nd stage plate. I resoldered the wire, the phone rang, I turned of the soldering iron and forgot about it. The next day I fired up the amp and voila...stable!!!!
From that day on I firmly believe that EVERYTHING makes a difference!

[Mark]

I think one thing we should do on this page is to record the levels of change incurred when building these amps.

What I mean by this is what wires in the amps layout make the greatest difference in the tonal response of the amplifier.

What valves work best in the amp, I have noticed that the guys at 18watt.com prefer EI 12AX7 pre-amp tubes as being most Mullard like and the JJ EL-84's as the most Mullard like output tubes.

While we too can try the EI AX7's and see if they work for us, the EL-34's is another matter. What brand do Komets' use?

The idea is to get a descending order of actions to implement to get the Express clone sounding "right."

After all there is no point in worrying about the colour dyes in the hook up wire when your layout isn't up to the task, or perhaps the tubes are at the end of there useful life.

Anyway, I hope that makes sense.

Yours Sincerely

Mark Abbott.

[snide]

I agree with Mark. At some point we have to quit worrying about impurities in our sheet metal screws and the type of plastic our knobs are made of and how they affect tone. As a pure hobbyist, I am more concerned about the bigger more tangible things that influence tone. I have tried Mullards and EI's in my express and they made a big difference in how the amp sounded. With a mix of both types of these tubes, the amp sounded closer to the tone the real express recordings that you think of. I already use JJ EL34's and they sound best out of the three sets I currently have. None of this is meant to down KF, he is without a doubt a legend and a guru. However, I think I'll take the esoteric B.S. with a grain of salt.

Eric

[RossH]

I'm not sure I've ever experienced people talking on this board much about...as you say, esoteric B.S. I think that the whole hi-fi world is something that you either believe and attempt to validate, or simply reject with no further effort. That's about the end of it. I do find it interesting to see how quick it converts to sarcasm with "magic knobs" and such.

Like with everything it is the easiest to get the quick and dirty 90% of things. The last 10% often costs the most and/or takes the most time. Most people are 90%-er's.

There was so much discussion in the ampage.org archives about the Express and the mojo that when given the opportunity to talk to KF I thought it would be nice to share with this group what he believes. Note that I preluded it with "his approach is so different" and "uncommon man". I too see he hangs in the small percentage.

Hopefully it was useful for someone to see the vantage point of the man regarding Express building.

My take on all this is when considering variation in tubes, room acoustics, tonal preference, variation in hearing, speaker differences, cabinet differences, musics types and a myriad of difference influential elements...the best approach you can take is to use your ears and tweak your amp until it makes YOU happy. I think that is essentially what this is all about.

Ross

[snide]

Ross,

Sorry you took offense to my post. I did not direct what I said at you. I have been told I have a sarcastic sense of humor. To me, I thought the whole thing sounded kind of far out and I was mildly amused. If I had known you would get upset by my post, I wouldn't have done it. Everyone has their own opinion about how cause and effect plays into amp building or anything for that matter. I have been an electrical engineer for over 20 years (yes we have colleges in alabama) so I need lots of empirical data to prove fringe theories. My job entails alot of electronic hardware design and prototyping but I have only recently started to fool around with tube amps. Once again, sorry for the misunderstanding.

Eric

[RossH]

Eric,

No misunderstanding or apology necessary. I didn't take offense or get upset. After talking to Ken and having the experience of his convictions I just thought it was worth restating or explaining the purpose of his post.

I had a pretty clear idea how most people would respond to his "craziness" with some form of suspicion and almost didn't post what I did. I did, however, because I hoped to add something to the group from the man who tends to build these amps that get all of the mojo-hype.

That is about the extent of the post. The "magic knobs" line really applies to a broad range of posts that I have experienced at ampage and other places.

Hope all is well and take care,
Ross

[Billy Batz]

As a fellow mathmatics major (physics) snide I can see where your comming from and you represent most mathmatically educated people in that we put far too much emphasis on numbers. You have to remember the natural physical world is far too complex to ever be explained as a function of a few values. So what good is empirical data when it only describes a certain aspect of something so infintessimaly complex. I dont know if Ken Fischer is right but I wont say he's wrong unless I have a better reason. My inclination is to believe it. One reason is that theres so many people out there with education getting in the way of knowledge who would tell me Im an idiot for thinking a transformer or cap could make an audible difference in an amp. Everyone here who has half decent ears and has replaced these things knows how much BS that is. You could use number to make a case for anything. The hard fact is what we would use to measure things may be much more accurate but never as encompasing (spelling?) as a human ear and where else should a musician base his opinions of sound? You may very well be right. Im in no position to argue but I think if you think of things the way I do it may help you to see another aspect of this old argument. I hope Ive made sense.

[Mark]

Like with everything it is the easiest to get the quick and dirty 90% of things. The last 10% often costs the most and/or takes the most time. Most people are 90%-er's.

Dear Ross

I do feel the 90% area is where we need the help, I feel amp layout is far more important than the colour of the wire used. I don't mind people saying these sort of theories, but I don't place much faith in the theories unless they can back up their theories, and I apply that rule across the board.

I do recall many years ago people such as Hogy saying that Express and Liverpool amps don't have any shielded cable in them, once I received a picture of a Liverpool amp (from a rock solid source), I realised that Express and Liverpool amps DO have shielded cable in them, and this particular amp also had a cap in series with a pot across the second plate resistor.

So You'll have to forgive me for being somewhat sceptical. but I feel that I have heard this kind of thing before. I would hate to see fellow builders waste time on the colour the wire they were using when their time would be better spent on the 90% items.

Okay, I've had my moment, and gotten that off my chest.